1. Field of the Invention
The present invention generally relates to a weld joint groove, and particularly, to a combination of plate edges prepared with a weld groove for a butt welding between plate members different of thickness from each other.
2. Description of Relevant Art
FIG. 1A is a section of a two-piece aluminium road wheel fabricated by a conventional butt welding, and FIG. 1B is an enlarged section of a welded joint portion of the road wheel of FIG. 1A.
As shown in FIG. 1A, the road wheel is fabricated by joining a prepared (right) edge of a rim 100 as a thin plate member to a prepared (left) edge of a disc 101 as a thick plate member, by way of a circumferential MIG welding full-circled at both radially inner side and radially outer side. The edges in concern are brought into abutment as shown in FIG. 1B, where they define a right-angled corner for the inner circumferential welding and a conventional V-shaped groove for the outer circumferential welding.
In other words, at the thin plate side, the edge of rim 100 is prepared in a bevelling manner to form a (left) groove face. At the thick plate side, the edge of disc 101 is likewise bevelled to form a (right) opposing groove face and cut to define an intermediate corner, leaving a step 101a with a height equivalent to a thickness difference between the members 2 and 3.
Then, the step 101a of disc 101 having a ring-like configuration is pressure-fitted in the prepared edge of rim 100 having a ring-like configuration to constitute a conventional edge combination (FIG. 1B), before they are joined together by a MIG welding along a circumferential length of the V-shaped groove at the radially outer side (i.e. upper side in the figure) and by a MIG welding along a circumferential length of the right-angled corner at the radially inner side (i.e. lower side in the figure), applying a circumferential fillet weld at an arrowed oblique direction, like a lap joint.
However, the outer circumferential welding to the conventional V-shaped groove tends to have a shallow penetration of weld at the thick plate side (i.e. disc 101 side) of the V-groove, relative to a penetration at the thin plate side (i.e. rim 100 side), thus resulting in an extremely limited range of allowance in accuracy for an electrode to be positioned at an aiming angle to achieve a favorable penetration at the thick plate side.
Moreover, in the conventional edge combination, a groove face simply terminates on an abutment face so that an erroneous edge preparation directly results in an erroneous groove depth. If this depth is insufficient, a resultant lack of fusion may give rise to an insufficient joint strength.
It thus requires an extremely high accuracy in both electrode positioning and edge preparation for the conventional edge combination to achieve a sufficient penetration for a secured favorable joint strength.